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| United States Patent |
5,573,795
|
|
Olsen
|
November 12, 1996
|
Method for treatment of potato fruit water
Abstract
In the method for treatment of potato fruit water the potato fruit water is
subjected to a heat treatment to at least 125.degree. C. for at least 3
minutes, whereafter the heat treated potato fruit water is cooled to a
temperature, at which enzymes are relatively stable, then enzymatically
treated with a proteinase, and finally concentrated to microbial
stability. Hereby a method for treatment of potato fruit water, which will
enable a commercially sound utilization of potato fruit water, is
provided.
| Inventors:
|
Olsen; Hans S. (Holte, DK)
|
| Assignee:
|
Novo Nordisk A/S (Bagsvaerd, DK)
|
| Appl. No.:
|
256323 |
| Filed:
|
July 8, 1994 |
| PCT Filed:
|
January 28, 1993
|
| PCT NO:
|
PCT/DK93/00030
|
| 371 Date:
|
July 8, 1994
|
| 102(e) Date:
|
July 8, 1994
|
| PCT PUB.NO.:
|
WO93/15616 |
| PCT PUB. Date:
|
August 19, 1993 |
Foreign Application Priority Data
| Current U.S. Class: |
426/53; 426/51; 426/52; 426/54; 426/63; 435/267; 435/274; 435/275; 435/277 |
| Intern'l Class: |
A23B 007/10; A23K 001/14; A23L 001/09; A23J 001/16 |
| Field of Search: |
426/53,52,51,54
435/274,275,267,277
|
References Cited
U.S. Patent Documents
| 4421682 | Dec., 1983 | Edwards et al. | 260/112.
|
| 4478940 | Oct., 1984 | Adler-Nissen et al. | 426/52.
|
| 4483874 | Nov., 1984 | Olsen | 426/44.
|
Other References
G. Richter et al., "Enzymatische Prozesse bei der Verarbeitung von
Kartoffeln", vol. 35, No. 4, pp. 113-118, 1983.
|
Primary Examiner: Kepplinger; Esther M.
Assistant Examiner: Koh; Choon P.
Attorney, Agent or Firm: Zelson, Esq.; Steve T., Harrington, Esq.; James J.
Claims
I claim:
1. Method for treatment of potato fruit water, wherein the potato fruit
water is subjected to a heat treatment to at least 125.degree. C. for at
least 3 minutes, whereafter the heat treated potato fruit water is cooled
to a temperature, at which enzymes are relatively stable, then
enzymatically treated with a proteinase, and finally concentrated to
microbial stability.
2. Method according to claim 1, wherein the potato fruit water is
preconcentrated, either directly upstream the heat treatment or directly
downstream the heat treatment.
3. Method according to claim 1, wherein the heat treatment is carried out
in a jet cooker.
4. Method according to claim 1, wherein the potato fruit water is subjected
to a heat treatment to at least 130.degree. C. for at least 3 minutes,
preferably for at least 5 minutes.
5. Method according to claim 1, wherein the heat treated potato fruit water
is cooled to a temperature between 60.degree. C. and 45.degree. C.
6. Method according to claim 1, wherein the enzymatic treatment of the
potato fruit water also comprises treatment with a starch degrading
enzyme.
7. Method according to claim 1, wherein the enzymatic treatment of the
potato fruit water also comprises treatment with a cell wall degrading
enzyme.
8. Method according to claim 1, wherein the protease is a neutral or
alkaline protease and wherein the enzymatic treatment is carried out at a
constant pH at or close to the activity optimum of the enzyme.
9. Method according to claim 7, wherein the cell wall degrading enzyme is
an SPS-ase preparation and the protease is Alcalase.RTM. protease.
10. Method according to claim 6, wherein the enzymatic treatment is carried
out sequentially and with pH adjustment in order to obtain optimal
activities of the enzymes.
11. Method according to claim 1, wherein the enzymatic reaction time is
between 1 and 6 hours, preferably between 2 and 3 hours.
12. Method according to claim 1, wherein the enzyme or enzymes are not
totally inactivated at the end of the enzymatic treatment.
13. Method according to claim 1, wherein the concentrated material is
spraydried.
Description
BACKGROUND OF THE INVENTION
The invention comprises a method for treatment of potato fruit water
(potato waste water). Potato fruit water is a certain fraction which
appears during the potato starch production. The disintegrated, clean
potato chips are first introduced into a decanter, the supernatant
therefrom being the potato fruit water; the residue is introduced into a
centrifugal sieve, from which two fractions are taken out, i.e. the potato
starch fraction and the potato pulp fraction. The annual production of
potato starch on a global basis is at least around 10.sup.6 tons, and the
corresponding volume of potato fruit water is at least around
4.times.10.sup.6 tons, with a dry matter content of at least 10.sup.5
tons.
Before the strict environmental regulations enforced today were passed,
potato fruit water was simply fed into the sewer system or sprayed onto
the fields. Another prior art attempt to solve the problem comprising the
utilization of potato fruit water in an environmentally acceptable and
economically sound manner has been established by utilization of heat
coagulators with subsequent recovery of the insoluble part of the protein
fraction by centrifugation as a concentrated protein precipitate. Also
attempts have been made to use ultrafiltration of the potato fruit water
in some potato processing plants. As around 50% of the total amount of the
potato protein is low molecular and non-coagulable, the mentioned methods
leave the non precipitable protein and the low molecular protein
components in solution. Thus these unwanted products will be present in
the waste water which has to be treated in waste water treatment plants or
utilized by other means. After introduction of the enviromental
regulations in many countries it became necessary to purify the potato
fruit water as efficient as possible before it was introduced into the
sewer system. This was a costly procedure, and the potato starch
manufacturer could derive no benefit from this expense unless valuable
products could be generated. It was suggested to concentrate the potato
fruit water in order to use it as an animal fodder; however, as the potato
fruit water without protein separation could not be concentrated more than
corresponding to about 25% dry matter, due to a sharp viscosity rise, and
as this percentage was considered too low for practical utilization of the
concentrated potato fruit water as an animal fodder, this suggestion did
never lead to a commercially sound utilization of potato fruit water.
SUMMARY OF THE INVENTION
Thus the purpose of the invention is the provision of a method for
treatment of potato fruit water, which will enable a commercially sound
utilization of potato fruit water.
The method according to the invention for treatment of potato fruit water
is characterized by the fact that the potato fruit water is subjected to a
heat treatment to at least 125.degree. C. for at least 3 minutes,
whereafter the heat treated fruit water is cooled to a temperature, at
which enzymes are relatively stable, then enzymatically treated with a
proteinase, and finally concentrated to microbial stability. The
concentrated end product is either a concentrated liquid with a content of
dry matter of 70% w/w or above, or a particle shaped material, such as a
powder or a granulate.
No upper limit for the duration of the heat treatment-is given; however, it
is a known fact that a heat treatment with a duration above a certain
critical value for this system, dependent of i.a. the pH, of the order of
magnitude around 10 minutes, will give rise to an unwanted reaction
between proteins and sugars (Maillard compositions), which will reduce the
nutritional value of the end product which is concentrated to microbial
stability.
Surprisingly it has been found that the potato fruit water, which is
treated according to the invention, can be concentrated to a dry matter
content of at least 50%, before the viscosity of the concentrate increases
so much that fouling and solidification occurs and that the thus treated
potato fruit water can be used in a commercially sound manner as a
microbially stable fodder. Also, surprisingly it has been found that both
the heat treatment and the enzyme treatment have to be carried out in
order to obtain the desired result.
Documentation for the fact that the method according to the invention
enables a sounder commercial utilization of the potato fruit water than
the most common prior art method for treatment of potato fruit water is
presented later in this specification.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the dependency between the degree of hydrolysis of the potato
fruit water proteins by the proteolytic treatment and the hydrolysis
reaction time, at different heat treatment times, with specific reference
to Example 1.
FIG. 2 shows the dependency between the degree of hydrolysis of the potato
fruit water proteins by the enzymatic treatment and the hydrolysis
reaction time 1) with no jet cooking and no enzyme (control), 2. with jet
cooking and proteolytic enzyme, and 3) with jet cooking and both
protcolytic enzyme and cell wall degrading enzyme, with specific reference
to Example 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In a preferred embodiment of the method according to the invention the
potato fruit water is preconcentrated, either directly upstream the heat
treatment or directly downstream the heat treatment. Directly upstream the
heat treatment means between the heat treatment and the decantation, and
directly downstream the heat treatment means between the heat treatment
and the enzymatic reaction. The preconcentration can be carried out by
evaporation or osmosis. In this manner a smaller liquid volume during the
enzymatic hydrolysis is obtained, which is an advantage from an investment
point of view. Also, in this manner, a smaller enzyme dosage can be used,
and thus a more economic process can be obtained.
In a preferred embodiment of the method according to the invention the
heating is carried out in a jet cooker. This is a convenient and effective
manner for performing the heating. A jet cooking process is a special heat
treatment in which efficient shearing and heating with direct steam is
achieved with continuous flow through a combining tube. A typical
commercial jet cooker, which can be used in the method according to the
invention is Hydroheater.RTM..
In a preferred embodiment of the method according to the invention the
potato fruit water is heated to at least 130.degree. C. for at least 3
minutes, preferably for at least 5 minutes. In this manner viscosity
problems are reduced in a very efficient manner.
In a preferred embodiment of the method according to the invention the heat
treated fruit water is cooled to a temperature between 60.degree. C. and
45.degree. C. In this manner it is secured that the enzymatic treatment is
performed satisfactorily.
In a preferred embodiment of the method according to the invention the
enzymatic treatment of the potato fruit water also comprises treatment
with a starch degrading enzyme. Hereby an even lower viscosity after the
enzyme reaction can be obtained.
In a preferred embodiment of the method according to the invention the
enzymatic treatment of the potato fruit water also comprises treatment
with a cell wall degrading enzyme. Hereby an even lower viscosity after
the enzyme reaction can be obtained.
In a preferred embodiment of the method according to the invention the
protease is a neutral or alkaline protease and the enzymatic treatment is
carried out at a constant pH at or close to the activity optimum of the
enzyme. Examples of neutral or alkaline enzymes are Neutrase.RTM.,
Alcalase.RTM., Savinase.RTM. and Esperase.RTM.. Hereby an efficient
degradation of the potato proteins is obtained.
In a preferred embodiment of the method according to the invention the cell
wall degrading enzyme is an SPS-ase preparation and the protease is
Alcalase.RTM. protease. This selection of cell wall degrading enzyme and
proteinase has been found to be efficient in regard to enzymatic
degradation.
In a preferred embodiment of the method according to the invention the
enzymatic treatment is carried out sequentially and with pH adjustment in
order to obtain optimal activities of the enzymes. In this manner the
utilization of the enzymatic activities is optimal.
In a preferred embodiment of the method according to the invention the
enzymatic reaction time is between 1 and 6 hours, preferably between 2 and
3 hours. If the reaction time is above 6 hours, the risk for putrefaction
increases, and if the reaction time is less than 1 hour, the cost of the
necessary amount of enzymes is will be unreasonably high.
In a preferred embodiment of the method according to the invention the
enzyme or enzymes are not totally inactivated at the end of the enzymatic
treatment. In this manner the enzymatic degradation can continue during
the concentration of the treated potato fruit water, and due to the
increasingly high concentration of dry matter during the concentration the
enzyme stability and thus the wanted degradation is high.
In a preferred embodiment of the method according to the invention the
concentrated material is spraydried. This is most convenient for
transportation and use as a fodder.
The parts of Example 1, which describe the method without any enzyme
addition or without jet cooking, are to be considered as comparisons
outside the scope of the invention.
In Examples 1 and 2 which exclusively demonstrate the effect of .the
enzyme(s) no final concentration to microbial stability was carried out;
in Examples 3 and 4 the final concentration to microbial stability was
carried out. Example 4 was exclusively carried out in pilot plant. Example
5 was carried out in order to illustrate the effect of various alkaline
proteases.
EXAMPLE 1
5000 liters of potato fruit water (1.30% dry matter, 0.76% N.times.6.25)
was centrifuged on a solids ejecting centrifuge type Westfalia SC 35 to
remove residual starch. The centrifugate was evaporated to approximately
400 liter (10% dry matter was aimed at) on a falling film evaporator (Niro
Atomizer type FF 200).
The thus produced concentrate was jet cooked by means of a Hydroheater.RTM.
at T=130.degree. C. and with a holding section which could be adjusted for
a treatment time of 1 minute, 2 minutes and 5 minutes. The cooked product
was continuously cooled through a plate heat exchanger to 50.degree. C.
Samples of this pre-evaporated and jet cooked potato fruit water
concentrate (PJPFWC) and a sample of non-jet cooked potato fruit water
concentrate were used for the following laboratory tests with the protease
Alcalase.RTM. or with the cell wall degrading enzyme SP-311 +
Alcalase.RTM.. Reference is made to H. Sejr Olsen: Aqueous extraction of
oil from seeds. In report EUR 11583 EN, Agriculture. Agricultural
refineries--A bridge from farm to industry, Edited by L. Munch and F.
Rexen, sponsored by the Commision of the European Communities. (1990)
(SP-311) and Product sheet from Novo Enzyme Process division B 318b-GB
(Alcalase.RTM.). SP-311 is a liquid preparation with an SPS-ase activity
of 50.00 SPSU/g of liquid preparation.
Laboratory Tests
800 g of PJPFWC was transferred to a 1 liter stirred reaction vessel,
termostatted to 50.degree. C. and adjusted to pH=4.50 by means of 6N HCl
for treatment with SP-311 and to pH=8.0 by means of 4N NaOH for treatment
with Alcalase.RTM.. During the treatment with Alcalase.RTM. pH was kept
constant at pH=8.0 by means of a pH-stat. The amount of 4N NaOH used was
recorded. Treatment with SP-311 was carried out for 24 hours and treatment
with Alcalase.RTM. was carried out for up to 150 minutes. Based on the
recorded amounts of 4N NaOH used for hydrolysis of the protein a
hydrolysis curve was drawn up for the DH% (DH = degree of hydrolysis)
versus time. The DH value was calculated by means of the following
formula:
##EQU1##
where B=consumption of base in mls
N.sub.B =normality of base
MP=mass of protein (N.times.6.25) in grams
.alpha.=degree of dissociation
h.sub.tot =the total number of peptide bonds per weight unit of the protein
(the value 8 g equivalents per kg of protein is used here).
Treatment with Alcalase.RTM. alone (no treatment with SP-311)
The effect of the jet cooking time on the performance of the hydrolysis of
the potato protein appear from the following data:
Effect of jet-cooking and proteinase treatment of potato fruit water
Enzyme: Alcalase.RTM. 2.4 L, Dosage, % E/P=2.00 (E is the weight of the
enzyme preparation, P is the weight of the substrate, in case the protein
(N.times.6.25)) pH-stat, pH=8.00, 4N NaOH. Temperature T=50.degree. C.
Jet cooking temperature 130.degree. C.
______________________________________
Jet cooking holding
time (minutes)
0 1 2 5
% Nx6.25 6.35 4.32 4.31 4.24
______________________________________
Reaction ml ml ml ml
Time (minutes)
NaOH NaOH NaOH NaOH
______________________________________
0 0.00 0.00 0.00 0.00
15 0.30 0.30 0.40 0.60
30 0.40 0.60 0.70 1.20
45 0.45 0.70 0.85 1.75
60 0.50 0.80 1.05 2.20
75 0.53 0.80 1.10 2.60
______________________________________
Reaction DH DH DH DH
Time (minutes)
% % % %
______________________________________
0 0.00 0.00 0.00 0.00
15 0.26 0.38 0.51 0.78
30 0.35 0.77 0.90 1.57
45 0.39 0.90 1.09 2.28
60 0.44 1.02 1.35 2.87
75 0.46 1.02 1.41 3.39
______________________________________
These data are further illustrated on FIG. 1, from which is appears that
the treatment for 5 minutes exhibits the greatest effect on the hydrolysis
of the protein part of the potato fruit water.
Treatment with Alcalase.RTM. and SP-311
Effect of jet cooking of pilot plant evaporated potato fruit water.
Enzyme 1: SP-311, Dosage, % E/D: 1.60 (D is the weight of the dry matter)
Enzyme 2: Alcalase.RTM. 2.4 L, Dosage, % E/P: 2.00
Reaction parameters:
Enzyme 1: pH=4.5, T=50.degree. C., reaction time: 24 hours
Enzyme 2: pH-stat, pH=8.00, 4N NaOH, T=50.degree. C.
Jet cooking temperature 130.degree. C. with a holding time of 5 minutes.
______________________________________
Enzyme None Enzyme 1 + 2
Enzyme 2
Nx6.25 6.35 4.23 4.23
______________________________________
Reaction ml ml ml
Time (minutes)
NaOH NaOH NaOH
______________________________________
0 0.00 0.00 0.00
15 0.30 0.70 0.45
30 0.38 1.25 0.70
45 0.45 1.65 0.95
60 0.50 2.00 1.15
75 0.53 2.28 1.35
90 2.50 1.55
105 2.70 1.80
120 2.90 2.00
135 3.00 2.15
150 3.10
______________________________________
Reaction DH DH DH
Time (minutes)
% % %
______________________________________
0 0.00 0.00 0.00
15 0.26 0.92 0.59
30 0.33 1.63 0.92
45 0.39 2.16 1.24
60 0.44 2.62 1.50
75 0.46 2.98 1.77
90 3.27 2.03
105 3.53 2.35
120 3.79 2.62
135 3.92 2.81
150 4.05
______________________________________
These data are further illustrated on FIG. 2, from which it appears that
jet cooking and the treatment with SP-311 and Alcalase .RTM. exhibits the
greatest effect on the hydrolysis of the protein part of the potato fruit
water.
EXAMPLE 2
5000 liters of potato fruit water (1.30% dry matter, 0.76% N.times.6.25)
was centrifuged on a solids ejecting centrifuge type Westfalia SC 35 to
remove residual starch. The centrifugate was evaporated to approximately
400 liters (10% dry matter was aimed at) on a falling film evaporator
(Niro Atomizer type FF 150).
The concentrate was jet cooked at T=130.degree. C. for 5 minutes by means
of a Hydroheater.RTM. and a holding section and subsequently continuously
cooled to 50.degree. C. through a plate heat exchanger. Samples of this
pre-evaporated and jet cooked potato fruit water concentrate (PJPFWC) were
used for the following laboratory tests in order to select an effective
enzyme system.
Laboratory tests:
800 g of PJPFWC was transferred to a 1 liter stirred reaction vessel,
termostatted to 50.degree. C. and adjusted to pH=4.50 by means of 6N HCl
for treatment with SP-311 or SP-348 (a Humicola insolens cellulase
experimental preparation, vide Bio-Feed Plus B 402c-GB) and to pH=8.0 by
means of 4N NaOH for treatment with Alcalase.RTM.. During the treatment
with Alcalase.RTM. pH was kept constant at pH=8.0 by means of a pH-stat.
Treatment with SP-311 or SP-348 was carried out for 24 hours and treatment
with Alcalase.RTM. was carried out for 2 hours. After the enzyme
treatments a portion of the reaction mixture was centrifuged at
3000.times.G (G=acceleration of earth gravity) for 30 minutes. The mass of
centrifugate was measured. Analyses were taken of the reaction mixture
before centrifugation and of the centrifugate for analyses of total dry
matter (DM) and nitrogen (Kjeldahl-N). Protein was calculated as
N.times.6.25.
The effect of the enzyme treatments is demonstrated in the tables below:
______________________________________
Data from the reaction mixture:
Enzymes
% of Reaction mixture
% of DM protein mass (g) % dry matter
% protein
______________________________________
Alcalase .RTM.
SP-311 2.4 L
0 0 110.4 10.02 4.51
1.6 0 111.6 9.48 4.35
1.6 0 109.2 9.35 4.22
0 2 111.0 10.02 4.51
1.6 2 117.2 9.35 4.22
P/DM av. 0.45
Alcalase .RTM.
SP-348 2.4 L
1.6 0 143.5 9.76 4.42
1.6 2 144.1 9.76 4.42
______________________________________
Data from the supernatants:
Supernatants
Enzymes % Indices
% of % of mass % dry pro- % % %
DM protein (g) matter
tein sludge
cih cip
______________________________________
Alcalase .RTM.
SP-311
2.4 L
0 0 91.88 8.11 2.99 16.8 80.9 66.3
1.6 0 92.8 7.94 3.10 16.8 83.8 71.3
1.6 0 86.3 7.95 3.10 21.0 85.0 73.5
0 2 95.7 8.75 3.45 13.8 87.3 76.6
1.6 2 104.1 9.23 3.78 11.2 98.7 89.6
Alcalase .RTM.
SP-348
2.4 L
1.6 0 114.4 6.37 3.00 20.3 65.3 68.0
1.6 2 123.0 7.33 3.38 14.6 75.1 76.4
______________________________________
The sludge content mentioned under indices is the actual content of
sediment measured in the reaction mixture.
The indices calculated are centrifugation indices calculated as follows:
For dry matter:
##EQU2##
where HC=% dry matter in centrifugate and
H=% dry matter in the reaction mixture
For protein:
##EQU3##
where PC=% protein in centrifugate
P=% protein in reaction mixture.
As appears from the indices the solubilisation was increased to the highest
values when both SP-311 and Alcalase.RTM. were used. SP-348 did not show
as high solubilisation of neither dry matter nor protein as SP-311. Also
the percentage of sludge content was the lowest when both SP-311 and
Alcalase.RTM. were used.
EXAMPLE 3
Pilot plant trial: PP-958
1500 liters of potato fruit water was jet cooked at 130.degree. C. by means
of the Hydroheater.RTM. jet cooker (300 liters/hour including a holding
cell of 25 liters). Thereby the holding time will be 5 minutes. The jet
cooked product was immediately cooled to 50.degree. C. and held for 30
minutes. Hereafter pH was elevated to pH=8.0 with 14.4 liters of 5.10N
NaOH.
The hydrolysis by means of Alcalase.RTM. 2.4 L was carried out with a
dosage of 0.5% of dry matter (E/D=0.5%). The hydrolysis was carried out to
DH=10%, controlled by the pH-stat. During the reaction the viscosity, %
sludge and .degree.BRIX was measured.
Parallel with the above hydrolysis hydrolyses in the laboratory were also
carried out. These reactions, which will be described in detail later in
this example were followed without pH-stat, but by measuring of osmolality
instead.
The next morning the pilot plant hydrolysate was evaporated on the Niro
FF-200 falling film evaporator. During concentration samples were taken
for measuring of viscosity using a Hake MV DIN measuring system.
Data from Pilot Plant
Enzyme 1: None, Dosage, % E/D: 0.00
Enzyme 2: Alcalase.RTM. 2.4 L, Dosage, % E/D: 0.50 Dosage, % E/P:1.05
Jet-cooking temperature: 130.degree. C. with a holding time of 5 minutes.
Enzyme reaction:
TABLE 1
______________________________________
DH-measurements
% Nx6.25 1.85
% dry matter 3.86
Reaction time DH %
(hours) (pH-stat)
______________________________________
0.00 0.00
0.25 0.41
0.50 0.61
1.00 1.22
19.00 2.64
______________________________________
Viscosity measurements during evaporation
TABLE 2
______________________________________
Dry matter and viscosity data from evaporation
CONCENTRATE Viscosity
Viscosity measurement
liters
.degree.Brix
.degree.Brix (calc.)
mPa*s Speed 1 Speed 4
______________________________________
1250 3.8 3.8 1.25 1.50 0.00
780 6.1 1.25 1.50 0.00
550 8.6 1.25 1.50 0.00
360 13.2 1.67 2.00 0.00
250 30.1 19.0 4.18 3.00 0.50
200 32.6 23.8 5.85 4.00 0.75
150 33.7 31.7 7.52 5.00 1.00
100 45.1 47.5 27.56 17.00 4.00
50 55.6 95.0 303.11 155.00 52.00
______________________________________
Data from laboratory
Jet-cooking: 130.degree. C. with a holding time of 5 minutes.
Trial I:
Enzyme 1: None, Dosage, % E/D: 0.00
Enzyme 2: Alcalase.RTM. 2.4 L, Dosage, % E/D: 0.50 Dosage, % E/P: 1.05
Enzyme 1: No reaction.
Enzyme 2: pH-stat, pH=8.50, 4.0N NaOH, T=50.degree. C.
Enzyme reaction data:
TABLE 3
______________________________________
DH-measurement
% Nx6.25 1.85
% dry matter 3.86
Reaction time DH %
(minutes) (pH-stat)
______________________________________
390 6.08
______________________________________
Trial II:
Enzyme 1: Viscozyme.RTM. 120 L (product sheet B 456a-GB from Novo Nordisk
A/S), Dosage, % E/D: 0.50
Enzyme 2: Alcalase.RTM. 2.4 L. Dosage, % E/D: 0.50 Dosage, % E/P: 1.05.
Enzyme 1: pH=4.81, T=50.degree. C., Reaction time 1 hour
Enzyme 2: pH-stat, pH=8.50, 4.0N NaOH, T=50.degree. C.
TABLE 4
______________________________________
DH-measurement
% Nx6.25 1.85
% dry matter 3.86
Reaction time DH %
(hours) (pH-stat)
______________________________________
2.40 7.18
______________________________________
A comparison between Table 3 and 4 shows that the combined use of a
protease and a cell wall degrading enzyme generated a higher DH than the
sole use of a protease.
EXAMPLE 4
This example was carried out in pilot plant.
1500 liters of potato fruit water was jet cooked at 130.degree. C. by means
of the Hydroheater.RTM. jet cooker (300 liters/hour including a holding
cell of 25 liters). The holding time is 5 minutes. The jet cooked product
was immediately cooled to 50.degree. C. and held for 30 minutes. pH was
measured and adjusted to pH=4.5 if above pH=5. 375 g of Viscozyme.RTM. 120
L (equivalent to 0.5% of dry matter) was added. The reaction was carried
out for 1 hour. Hereafter pH was elevated to pH 8.0 by means of 18.6
liters of 5.10N NaOH. Hydrolysis by Alcalase.RTM. 2.4 L was carried out by
means of a dosage of 0.5% of dry matter (E/D=0.5%). Also in this case 375
g of Viscozyme.RTM. 120 L was added. The hydrolysis was carried out to
DH=10%, controlled by the pH-stat. During the reaction the viscosity, %
sludge and .degree.Brix was measured. The next morning the hydrolysate was
evaporated on the Niro FF-200 falling film evaporator. During
concentration samples were taken in order to measure the viscosity by
means of a Hake MV DIN measuring system.
Enzyme 1: Viscozyme.RTM. 120 L, Dosage, % E/D: 0.50
Enzyme 2: Alcalase.RTM. 2.4 L, Dosage, % E/D: 0.50 Dosage, % E/P: 1.05
Reaction parameters:
Enzyme 1: pH=4.95, T=50.degree. C., Reaction time: 1 hour
Enzyme 2: pH-stat, pH=8.00, 5.1N NaOH, T=50.degree. C.
TABLE 5
______________________________________
DH-measurements
% Protein 1.85 1.85
% dry matter 3.86 3.86
Reaction time DH % DH %
(hours) (pH-stat)
(osmometer)
______________________________________
1.00 0.14 0.00
2.00 0.49 0.00
2.50 0.81 7.44
2.67 0.94 7.44
18.50 4.07 20.30
______________________________________
Viscosity Measurements During Evaporation
TABLE 6
______________________________________
Dry matter and viscosity data from evaporation
CONCENTRATE Viscosity
Viscosity measurement
liters
.degree.Brix
.degree.Brix (calc.)
mPa*s Speed 1 Speed 4
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1200 8.0 8.0 9 11 0
1000 9.5 9.6 6 7 0
950 10.0 10.1 8 10 0
800 12.1 12.0 9 11 0
600 16.5 16.0 8 10 0
500 19.2 19.2 10 12 0
400 20.8 24.0 10 12 0
300 30.8 32.0 16 15 1
200 41.0 48.0 16 15 1
150 -- 64.0 23 20 2
100 54.1 96.0 33 28 3
80 62.1 120.0 144 65 27
60 61.1 160.0 144 64 27
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Due to the treatment with Viscozyme.RTM. 120 L a lower viscosity was found
in the concentrated hydrolysate. Thereby it was possible to concentrate to
a higher dry matter content before fouling appears on the evaporator
tubes.
EXAMPLE 5
This example was carried out in pilot plant in order to illustrate the
effect of various alkaline proteases.
The below indicated plan and flow-sheet was followed:
##STR1##
Procedure
To 785 liters of fruit water of 6.0.degree. Brix was added 350 ml of
antifoaming agent PP-2000. The mixture was vacuum evaporated on a falling
film evaporator (Niro Atomizer type FF 200). The temperature of the
product before calandria was 35.degree.-40.degree. C. and the temperature
of the product leaving the calandria was 60.degree.-65.degree. C. After
190 minutes 427 liters of condensate and 358 liters of concentrate of
11.6.degree. Brix was collected.
The concentrate was jet cooked in a Hydroheater.RTM. at T=135.degree. C.
with a holding time of 5 minutes. After a holding section the product was
cooled to 50.degree. C. through a plate heat exchanger to 50.degree. C. By
means of this method 324 kg of preconcentrated and jet cooked material was
produced. The concentrate was analysed for dry matter (9.7% dry matter).
Three portions each consisting of 108 kg of this heat treated concentrate
was adjusted to pH=8.5 by means of 5N NaOH. Subsequently the heat treated
and pH adjusted concentrate was enzyme treated with 0.5% of the alkaline
proteases Esperase.RTM. 8.0 L type A, Savinase.RTM. 8.0 L or Alcalase.RTM.
2.4 L, respectively. During each hydrolysis samples were drawn as a
function of the time, and 10 ml of the reaction mixture was centrifuged at
4200 rpm at a laboratory centrifuge. The supernatant was analysed for pH,
osmolality, .degree.Brix and % sludge.
After 240 minutes of reaction each of the hydrolysed mixtures were
evaporated on a LUWA evaporator at a product temperature of
45.degree.-60.degree. C., until the viscosity of the concentrate increased
to a value, at which the power consumption for the rotor of the LUWA
evaporator was 3-4 times the value of the power consumption at the
beginning of the evaporation.
The data for the three trial are shown in the following three tables:
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Time, Osmolality
minutes pH .degree.Brix
increase
% Sludge
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Enzyme: Esperase .RTM. 8.0 L type A.
1 8.48 9.7 2 17
10 8.45 9.7 8 16
30 8.41 9.8 17 16
60 8.39 10.1 17 15
90 8.36 10.1 25 14
120 8.30 10.3 24 14
150 10.4 25 14
180 10.9 35 13
210 10.6 34 14
240 8.22 10.7 33 14
______________________________________
Concentrate: 21 kg of 53.2.degree. Brix.
Enzyme: Savinase .RTM. 8.0 L
0 8.50 9.6 0 18
1 8.48 9.7 6 18
10 8.46 9.7 1 17
30 8.38 9.9 9 17
60 8.32 9.9 18 17
90 10.0 16 17
120 10.2 21 15
150 10.3 22 15
180 10.3 17 15
210 10.4 23 15
240 8.05 10.5 19 15
______________________________________
Concentrate: 13 kg of 56.9.degree. Brix.
Enzyme: Alcalase .RTM. 2.4 L
1 8.52 9.6 0 18
10 8.46 9.8 -4 18
30 8.41 9.9 -7 17
60 8.32 10.3 9 17
90 8.24 10.5 10 17
120 8.20 10.6 6 17
150 8.14 10.9 38 16
180 8.10 11.0 31 16
210 8.05 11.2 38 14
240 8.02 11.3 68 14
______________________________________
Concentrate: 14 kg of 65.0.degree. Brix.
Even in consideration of the fact that there were some uncertaincy in the
determination of the osmolality in the trial with Alcalase .RTM.2.4 L it
can be concluded that this trial showed a more effective degradation of
the components of the potato fruit water in comparison to the two other
alkaline proteases.
Documentation For Economic Superiority
In the following a typical embodiment of the method according to the
invention is described, with emphasis upon the economic aspects thereof.
Also, as comparison, a typical corresponding prior art method is
described, also with emphasis upon the economic aspects thereof.
The embodiment of the method according to the invention is carried out as
shown in the below indicated flow sheet.
##STR2##
In more detail, this embodiment of the method according to the invention is
carried out as follows.
1. Potato fruit water is evaporated to around 10.degree. Brix by means of
an evaporation temperature of 45.degree.-60.degree. C. The evaporation is
carried out as a batch process with recirculation through the evaporator.
During the evaporation the capacity (amount of condensate/minute), the
temperature and the concentration in .degree.Brix in the retentate is
followed as a function of time.
2. The concentrate is jet cooked at 135.degree. C. for 5 minutes. Samples
for determination of osmolality, .degree.Brix, pH and amount of sludge
before and after jet cooking are taken. The total amount of dry matter is
determined on a fast drier.
3. The reaction mixture is thermostatted at 50.degree. C. The pH value is
adjusted to 4.5-5.0. If above 5.0 the adjustment is made by means of
phosphoric acid.
4. Viscozyme.RTM. is now added in a dosage of 0.50% Viscozyme.RTM., based
on dry matter. The reaction is followed with centrifuge samples in order
to determine .degree.Brix, osmolality and sludge volume. When the
parameter values have levelled off (after around 2 hours), the reaction is
stopped by adjustment of pH to 8.0 with NaOH.
5. Now hydrolysis is carried out without pH-stat by means of 0.5%
Alcalase.RTM. 2.4 L, based on dry matter. This reaction, too, is followed
by means of centrifuge samples for determination of .degree.Brix,
osmolality and sludge volume. When the parameter values have levelled off,
the method is continued as indicated below, without inactivation.
6. The material is evaporated to approx. 50.degree. Brix. During the
evaporation samples are taken out from the concentrate tube, as a function
of time, in order to determine the osmolality, .degree.Brix, pH and sludge
volume.
If the above indicated embodiment of the method according to the invention
is based upon a throughput of 50 tons of potatoes/hour corresponding to
5,000 tons of potatoes/year, potato fruit water corresponding to approx.
56 m.sup.3 /hour or 117,000 m.sup.3 /year with a dry matter content of
3.5% will be produced.
If this amount of potato fruit water should be fed to the sewer (prior art
method), treatment thereof in a biological purification plant would cost
approx. 16-18 Danish kr./m.sup.3 or approx. 2,106,000 Danish kr./year.
The economic aspects in regard to the corresponding above indicated
embodiment of the method according to the invention appear from the below
list of items.
______________________________________
Danish kr.
______________________________________
Chemicals
Antifoaming agents, 25 tons
75,000
NaOH pearls, 170 tons 850,000
Enzymes
Viscozyme .RTM., 12.5 tons 1,500,000
Alcalase .RTM., 12.5 tons 1,250,000
Energy for evaporation 1,100,000
Salaries 750,000
Interest and provision for depreciation of an
1,200,000
investment of 6 mio. Danish kr.
Total expenses 6,725,000
Expected income from sales of evaporated concen-
12,300,000
trate (8,200 tons with a price of 1.5 Danish kr./kg)
Profit, calculated in relation to prior art method
7,681,000
______________________________________
It thus appears that the method according to the invention exhibits an
economic superiority in comparison to prior art.
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